<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>TRB Publications Index</title><link>http://pubsindex.trb.org/</link><atom:link href="http://pubsindex.trb.org/common/TRIS Suite/feeds/rss.aspx?tc=NN%3AQpm%2A" rel="self" type="application/rss+xml" /><description></description><language>en-us</language><copyright>Copyright © 2015. National Academy of Sciences. All rights reserved.</copyright><docs>http://blogs.law.harvard.edu/tech/rss</docs><managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor><webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster><image><title>TRB Publications Index</title><url>http://pubsindex.trb.org/Images/PageHeader-wTitle.png</url><link>http://pubsindex.trb.org/</link></image><item><title>Tire-Derived Aggregate Modified Using Postconsumer Recycled Plastics for Subsurface Pavement Applications: A Study of Absorption and Swelling Effects</title><link>http://pubsindex.trb.org/view/2569804</link><description><![CDATA[The major objective of this research study, believed to be the first of its kind, was to explore the swelling and absorption rate of tire-derived aggregate (TDA) modified using postconsumer recycled (PCR) plastics in optimum blend proportions. Further, TDA was utilized in developing plastics-modified rubberized asphalt mixtures through an innovative semi-dry approach aimed at applications in subsurface layers, such as the base or subbase of a pavement system. The research included: (i) physical and thermochemical characterization of raw materials; (ii) blending of 16 combinations of PCR plastics-modified asphalt (PA) binder; (iii) rheological assessment of PA blends, including performance grade, multiple stress creep recovery, and optimization; (iv) preparation of 18 combinations of modified TDA (MTDA) products utilizing optimized PA blend; (v) asphalt absorption tests on TDA and MTDA to determine swelling and asphalt absorption rates; and (vi) microscopy of MTDA particles. Thermochemical characterization revealed promising binding compatibility of TDA, PCR plastics, and hydraulic lime (HL), owing to their distinct thermal and chemical properties, while rheological assessment confirmed that PA blends with higher polyethylene terephthalate dosages significantly improved rutting resistance and elasticity for TDA modification. Additionally, the inclusion of PCR plastics and HL in MTDA reduced the absorption capacity and uncontrolled swelling of the unprocessed TDA three- or four-fold. It is envisioned that this study will promote a feasible waste management solution to address recycling of both waste tires and plastics by conserving natural resources and pave the way to create perpetual and resilient infrastructure.]]></description><pubDate>Tue, 01 Jul 2025 14:39:19 GMT</pubDate><guid>http://pubsindex.trb.org/view/2569804</guid></item><item><title>Laboratory Characterizations of Tire-Derived Aggregate–Fine-Grained Soil Mixtures for Highway Applications</title><link>http://pubsindex.trb.org/view/2567043</link><description><![CDATA[In this experimental study, comprehensive laboratory tests were conducted to investigate the mechanical properties of tire-derived aggregate (TDA) Type A and TDA–soil mixtures applicable in the construction of drainage layer, embankment fill, and backfill materials for retaining walls, pipes, and bridge abutments. This study was an investigation of the mechanical properties of TDA, as a lightweight material, and TDA–fine-grained soil mixtures for different mix ratios of 15%, 20%, 35%, 40%, 50%, and 60% of TDA-A relative to the dry weight of the soil. Various composite samples were tested using triaxial and direct shear apparatus. Measured properties include specific gravity, Proctor maximum dry density and optimal water content, unconfined compressive strength, peak compressive strength, shear strength, and hydraulic conductivity. Test results revealed that the addition of TDA to the soil significantly improved the compressive strength under confinement and permeability of the composite specimens. Based on the test results and supporting data from intensive literature reviews, the TDA–soil mixture showed very encouraging results for use in civil engineering applications as a lightweight backfill material.]]></description><pubDate>Mon, 23 Jun 2025 08:44:37 GMT</pubDate><guid>http://pubsindex.trb.org/view/2567043</guid></item><item><title>Low-cost Sensing System for the Detection and Classification of Wide-Base Tire Types and Distribution at the Network Level</title><link>http://pubsindex.trb.org/view/2548680</link><description><![CDATA[This Innovations Deserving Exploratory Analysis (IDEA) project report details developing, implementing, and testing an innovative low-cost sensing system designed to detect and classify wide-base tires (WBTs), monitor wheel wander, and analyze vehicle classifications in real time. This technology addresses critical gaps in pavement management and traffic monitoring by providing accurate and affordable data on tire types and distributions, which is crucial for understanding and mitigating pavement wear patterns. The core innovation is a sensor system embedded in EPDM (Ethylene Propylene Diene Terpolymer) rubber strips, utilizing force transducer technology to detect tire widths, vehicle classifications, and wheel wander at highway speeds. The system can function as both a portable or permanent installation, offering flexibility for diverse applications across transportation infrastructure. Unlike traditional weigh-in-motion (WIM) systems, which are expensive and limited in scope, this solution captures detailed, real-time data that include: Tire width (e.g., distinguishing WBTs from dual tires); Vehicle classification (axle count, wheelbase, and spacing); and Wheel wander and tire distribution patterns. The system is designed for scalability and cost-effectiveness, enabling deployment at network levels by state departments of transportation (DOTs), the Federal Highway Administration (FHWA), and other transportation agencies.]]></description><pubDate>Sat, 03 May 2025 16:36:17 GMT</pubDate><guid>http://pubsindex.trb.org/view/2548680</guid></item><item><title>Construction of Electrically Heated Pavement Using Recycled Waste Rubber Tires</title><link>http://pubsindex.trb.org/view/2442074</link><description><![CDATA[Accumulated snow on roads presents a dual risk of accidents and financial losses. Conventional de-icing methods, which rely on chemicals, salt, and heavy machinery, are unsustainable and detrimental to both the environment and infrastructure. Furthermore, they demand significant labor and pose hazards in densely populated areas. In response, heated pavement systems such as hydronic and electrically conductive concrete (ECON) have gained traction for mitigating snow accumulation on roads. However, the use of carbon fiber and carbon black in ECON raises costs and depletes valuable resources. This research introduces an inventive and sustainable approach to address snow accumulation on rigid pavements during winter. The proposed method utilizes waste rubber tires (WRT) as heating pads for pavements. The steel wires within these tires generate heat when an electric current is applied. The study validates this method by embedding WRT across the rigid pavement, creating an electric circuit connected to a power source. The rubber tire pads demonstrated high efficiency in conducting electricity, significantly increasing temperatures with a 6?V supply. The tire rubber pads reached up to 46.3°C and 60°C using different electric circuit designs, compared with the ambient temperature of 22°C–23°C. Embedded in concrete, these pads raised surface temperatures to as high as 52°C, effectively melting snow, ice cubes, and crushed ice within 1?h. This method provides an environmentally friendly and sustainable solution. This research unveils a groundbreaking strategy for de-icing snow on rigid pavements, offering a sustainable substitute for traditional de-icing procedures and addressing resource depletion.]]></description><pubDate>Sat, 19 Oct 2024 16:17:37 GMT</pubDate><guid>http://pubsindex.trb.org/view/2442074</guid></item><item><title>Studded Tires Versus Pavement Markings: A Collision Course</title><link>http://pubsindex.trb.org/view/2419996</link><description><![CDATA[An automobile equipped with four studded tires, each containing 72 studs, has, at all times, approximately 25 to 30 studs facing the pavement. These tungsten carbide studs protrude 0.030 to 0.060 in. below the tread surface and are designed to wear at about the same rate as the tire, so that stud protrusion should remain nearly constant. Studs do not have any built-in respect for pavement markings and impose a new dimension to the difficulty of maintaining pavement markings. Studded tires and pavement markings contribute to traffic safety each in their own way. The problem is that conventional traffic markings have, at present, a relatively short service life. The widespread use of studded tires adds an additional burden on these already overworked materials. Further discussion of this problem leads to the conclusion that the future acceptance and use of studded tires is of great importance to those persons involved with the safety of the motorist, the maintenance of the highways, and the design of the next generation of pavements and pavement marking materials. Studies need to be made of the cost-effectiveness of studded tires, the cost-effectiveness of pavement markings, the rate of damage inflicted on pavement markings by studded tires, and the course of action to be recommended. The current trend appears to be toward general acceptance of studded tires, which means that highway departments must reevaluate their pavement marking practices and the materials used.]]></description><pubDate>Mon, 23 Sep 2024 11:18:43 GMT</pubDate><guid>http://pubsindex.trb.org/view/2419996</guid></item><item><title>Feasibility Assessment of Utilization of Used Automobile Tire in Concrete</title><link>http://pubsindex.trb.org/view/2335290</link><description><![CDATA[Millions of used automobile tires are produced every year, which is an ever-growing issue for solid waste management authorities. Using waste tires to generate fuels or dumping them in landfills is not a sustainable practice. This study aimed to explore fresh, mechanical, and durability characteristics of concrete integrating waste tires in the forms of ground tire rubber (GTR) as a replacement for sand and micronized rubber powder (MRP) as a replacement for cement. Eight concrete mixes were prepared using 5%, 10%, and 15% GTR and 4%, 7%, and 10% MRP to determine slump, unit weight, air content, compressive, tensile, and flexural strength, elastic modulus, drying shrinkage, alkali-silica reaction (ASR), sulfate attack expansion, and scaling resistance. Experimental results showed that adding GTR and MRP to concrete reduced workability and increased air content in comparison to the control mixture. Besides, concrete containing 15% GTR or 10% MRP satisfied the American Concrete Institute (ACI) durability freeze-thaw criterion. For mechanical properties, adding GTR and MRP to concrete reduced compressive, tensile, and flexural strength and elastic modulus. Furthermore, increasing GTR and MRP amounts in concrete slightly increased drying shrinkage and sulfate attack expansion. However, the addition of GTR and MRP in concrete substantially reduced the ASR expansion. The effect of deicing chemicals was relatively severe on GTR-modified concrete compared to MRP-modified concrete for scaling resistance. Considering the overall performance, 5% GTR or 4% MRP will be the optimum content for producing durable and sustainable concrete.]]></description><pubDate>Tue, 13 Feb 2024 16:35:43 GMT</pubDate><guid>http://pubsindex.trb.org/view/2335290</guid></item><item><title>Effect of Tire Chips on the Shear Behavior of Steel Slag and Granite Ballast Mixture</title><link>http://pubsindex.trb.org/view/2319963</link><description><![CDATA[With a view to reduce burden on natural resources, the use of steel slag ballast (SSB) as an alternative to the conventional granite ballast (GB) is explored in the current study. The shear behavior of GB, SSB, and slag-GB mixture with and without tire chips (TC) was evaluated under direct shear conditions. The test results indicated that SSB exhibits significantly higher friction and dilation angles (f and ?) and lower particle breakage (Bg) when compared with GB. Furthermore, it was observed that, with the addition of TC, the magnitude of f, ?, and Bg of both granite and steel slag samples reduced considerably. Moreover, the friction and dilation angles of slag-GB mixture were found to be directly dependent on the proportion of slag in the mixture. For instance, the values of f, ?, and Bg in the case of SSB20 (20% SSB and 80% GB) were 59.36°, 13.35°, and 8.26% when compared with 58.31°, 12.98°, and 8.51% in the case of GB, and 61.66°, 15.35°, and 6.81% of SSB. However, SSB80 was found to exhibit an almost similar value of f (i.e., 61.51°) as that of SSB but with a lower value of ? (14.89°). In this context, the optimum content of slag in the slag-GB mixture may be considered as 80%. Furthermore, the optimal range of TC to be added was determined to be 4% to 8.6% for SSB80 to attain a friction angle similar to that of GB.]]></description><pubDate>Fri, 12 Jan 2024 15:02:15 GMT</pubDate><guid>http://pubsindex.trb.org/view/2319963</guid></item><item><title>New Approach to Determining the Roughness of Bicycle Roads</title><link>http://pubsindex.trb.org/view/2218950</link><description><![CDATA[The international roughness index (IRI) is one of the important criterion used to determine the roughness of roads. Various devices are available to determine IRI, however, they are mostly used to determine the condition of highways. Studies to determine the roughness of nonmotorized roads, such as bicycle roads, which have become increasingly important in recent years, are limited. Therefore, this study presents a cost-effective roughness measurement method that can measure both highways and nonmotorized roads. For this, a mountain bike was used as the test vehicle, and for the first time, the stiffness and damping coefficients of the bicycle tire were taken into account when calculating the IRI. First, the stiffness and damping coefficients of the bicycle’s front tire were calculated. These coefficients were then used as input data for the equation of motion with one degree of freedom, and the IRI was calculated. The 660-m long divided highway (1,320?m in total) on the Bursa Uludagg University campus was chosen as the test road. A laser profilometer device was used to quantify the reference IRI values of this test road. The same road was then measured by bicycle. The obtained results were evaluated using mean absolute percent error, mean absolute error, root mean square error, and mean square error metrics. All these indicators showed very promising results, suggesting that this new method could be a cost-effective and reliable approach to determining the IRI of highways, especially nonmotorized roads.]]></description><pubDate>Mon, 24 Jul 2023 16:36:48 GMT</pubDate><guid>http://pubsindex.trb.org/view/2218950</guid></item><item><title>Effect of Vehicle Speed and Weight on Raveling of Chip Seal Constructed Using Mineral and Tire Derived Aggregate</title><link>http://pubsindex.trb.org/view/2205331</link><description><![CDATA[The characteristics of the load applied by traffic, namely, vehicle speed and load magnitude, play a critical role in the raveling performance of chip seal pavement, which is often overlooked in literature. Furthermore, a sustainable chip seal constructed out of tire derived aggregate (TDA) has been recently introduced. Unlike mineral aggregate, rubber is a time-dependent material, and its properties are greatly influenced by the magnitude and rate of loading. Introducing TDA in chip seal has increased the significance and need to investigate the effects of vehicle speed and load on chip seal. This study investigated the raveling performance of different chip seal specimens constructed out of mineral and TDA, as well as a hybrid tire derived–mineral aggregate, under various loading speeds and magnitudes using a small-wheel traffic simulation device. The findings revealed that both load and speed significantly affect the texture loss of conventional and TDA chip seals, but in opposite ways. Conventional chip seals experienced increased texture loss with higher load and speed, while TDA chip seals showed a decrease. The use of TDA as an aggregate in chip seal resulted in a 23% reduction in macrotexture loss under increased load and a 56% reduction in macrotexture loss under increased speed compared with conventional chip seal. This improved performance is attributed to the dynamic properties of TDA, such as internal hysteresis, time-dependent behavior, and load transmissibility.]]></description><pubDate>Thu, 06 Jul 2023 17:09:52 GMT</pubDate><guid>http://pubsindex.trb.org/view/2205331</guid></item><item><title>Use of Mobile Sensing Data for Assessing Vibration Impact of E-Scooters with Different Wheel Sizes</title><link>http://pubsindex.trb.org/view/2138537</link><description><![CDATA[With the growing demand of shared electric scooters (e-scooters) for short-distance trips in urban areas, their safety issues have received significant attention from various stakeholders. In general, e-scooter riders encounter more vibrations compared with users of other transportation modes such as bicycles that typically have larger wheels and better suspension systems. Such riding experience may lead to discomfort, affect riders’ health, and increase riding risk. Intuitively, increasing e-scooters’ wheel sizes may provide safer and more comfortable riding experience. However, this assumption has not been well tested. The main objective of this paper is to curtail this gap by quantitatively assessing the impacts riders experienced, through the use mobile sensing data. Specifically, a mobile sensing platform was deployed on e-scooters with different wheel sizes to continuously measure encountered vibrations. Then, the instrumented e-scooters were ridden on routes with different pavement materials. Finally, the collected data were further processed and analyzed to evaluate various riding issues in each riding scenario. The comparative results suggest that e-scooters with larger wheels can efficiently alleviate vibrations during a ride compared with those with smaller wheels. To improve riding experience and safety, it is beneficial to use larger-wheel e-scooters, given other similar riding conditions.]]></description><pubDate>Mon, 20 Mar 2023 16:18:20 GMT</pubDate><guid>http://pubsindex.trb.org/view/2138537</guid></item><item><title>Demonstration Project for Ground Tire Rubber and Post-Consumer Recycled Plastic-Modified Asphalt Mixtures</title><link>http://pubsindex.trb.org/view/1920631</link><description><![CDATA[Research has demonstrated that asphalt pavements can be a strategic destination for some of the major streams of waste materials around the globe, such as scrap tires and plastics. Ground tire rubber (GTR) from scrap tires has been used in asphalt pavements since the 1960s but has yet to approach its full potential in relation to market adoption. The heightened restrictions imposed by China in relation to waste stream contamination in 2018 have catalyzed research on incorporating post-consumer recycled (PCR) plastics into asphalt pavements. A field demonstration project was carried out in Columbia, MO to evaluate modern recycled plastic and GTR additives in an asphalt pavement overlay. The demonstration focused on dry-process modification, which requires minimal alterations to an existing asphalt plant and allows a higher amount of recyclates to be utilized. The project was also designed to assist in the Missouri Department of Transportation’s early roll-out of balanced mix design asphalt design and quality assurance specifications. The results of the study indicated the viability of dry-process GTR and PCR plastic additives used with neat (unmodified) asphalt binder as an alternative to binders modified with virgin polymers, chemical treatments, or both, in a wet process. The results of the study also suggest the viability of hybrid wet polymer-modified binder with dry-process PCR plastic as a greener alternative to binders modified with virgin polymers, chemical treatments, or both. Future studies will be needed to examine additional PCR plastic streams, especially mixed polymer streams.]]></description><pubDate>Mon, 28 Feb 2022 17:05:07 GMT</pubDate><guid>http://pubsindex.trb.org/view/1920631</guid></item><item><title>Near Surface Pavement Response Using a Numerically Approximated Tire Contact Pressure From Inverse Analysis</title><link>http://pubsindex.trb.org/view/1910800</link><description><![CDATA[Current military flexible pavement design is based on a mechanistic–empirical methodology, in which the mechanistic response is sometimes computed using a layered elastic analysis (LEA) approach. The assumption in most LEA computer programs is that the load is applied uniformly over a circular contact area. In most cases where subgrade rutting failures are expected, this assumption provides satisfactory results when the responses are computed in the subgrade far from the applied load. But in the case of thin asphalt structures with marginal base materials, base failures could potentially occur and the effects of nonuniform tire contact pressure could be more prominent. This study presents a numerical approximation method of obtaining a possible nonuniform, noncircular tire contact pressure distribution using the LEA framework. The iterative procedure attempts to match the true contact area and satisfies the requirements of static equilibrium using inverse analysis. The results showed that the numerical approach provided more reasonable near surface responses compared with the uniform contact pressure assumption and was noticeably more efficient than its finite element counterpart. The findings suggested that the numerical procedure could provide a sound mechanistic alternative for designing thin asphalt pavements with marginal base materials where base failures are likely to occur.]]></description><pubDate>Fri, 11 Feb 2022 17:13:56 GMT</pubDate><guid>http://pubsindex.trb.org/view/1910800</guid></item><item><title>Dynamic Modal Analysis of a Passenger Bus: Theoretical and Numerical Studies</title><link>http://pubsindex.trb.org/view/1877839</link><description><![CDATA[The dynamic assessment of a passenger bus is of the highest importance when aiming at high safety standards and low emissions for environmental sustainability. This work studies the dynamic response of a bus considering its modal analysis, for which simple dynamic models were developed for fast determination of the lowest frequencies, mainly arising from the suspension flexibility. In addition, complex natural vibration modes, impossible to determine using simplified models, were calculated via finite element method (FEM) modeling. To study the tire elastic behavior, as the key link between the vehicle and the road, specific deformation models, leading to a stiffness matrix to be combined with that of the vehicle spring suspension at each wheel/axis, were developed. This study aims at proposing a set of mathematical formulations to describe the modal behavior of passenger buses in detail, which could be applicable in any other long vehicle with similar conditions. Two main factors are studied, namely the suspension and the tire deformation effect. An acceptable agreement was verified between the simplified approach and FEM model results for the evaluation of natural frequencies and associated modes.]]></description><pubDate>Mon, 13 Sep 2021 16:08:58 GMT</pubDate><guid>http://pubsindex.trb.org/view/1877839</guid></item><item><title>Thermomechanical Coupling of a Hyper-viscoelastic Truck Tire and a Pavement Layer and its Impact on Three-dimensional Contact Stresses</title><link>http://pubsindex.trb.org/view/1867325</link><description><![CDATA[A thermomechanical coupling between a hyper-viscoelastic tire and a representative pavement layer was conducted to assess the effect of various temperature profiles on the mechanical behavior of a rolling truck tire. The two deformable bodies, namely the tire and pavement layer, were subjected to steady-state-uniform and non-uniform temperature profiles to identify the significance of considering temperature as a variable in contact-stress prediction. A myriad of ambient, internal air, and pavement-surface conditions were simulated, along with combinations of applied tire load, tire-inflation pressure, and traveling speed. Analogous to winter, the low temperature profiles induced a smaller tire-pavement contact area that resulted in stress localization. On the other hand, under high temperature conditions during the summer, higher tire deformation resulted in lower contact-stress magnitudes owing to an increase in the tire-pavement contact area. In both conditions, vertical and longitudinal contact stresses are impacted, while transverse contact stresses are relatively less affected. This behavior, however, may change under a non-free-rolling condition, such as braking, accelerating, and cornering. By incorporating temperature into the tire-pavement interaction model, changes in the magnitude and distribution of the three-dimensional contact stresses were manifested. This would have a direct implication on the rolling resistance and near-surface behavior of flexible pavements.]]></description><pubDate>Mon, 26 Jul 2021 17:59:37 GMT</pubDate><guid>http://pubsindex.trb.org/view/1867325</guid></item><item><title>Critical State Model of Sand-Tire Derived Aggregate Mixtures Based on Triaxial Tests</title><link>http://pubsindex.trb.org/view/1860414</link><description><![CDATA[This study is part of an environmental experimental program on the use of scrap automobile tires for geotechnical applications. Different types of laboratory tests were conducted to determine the elastic, plastic, and creep parameters of tire derived aggregate (TDA)-sand granulated mixtures. However, this paper emphasizes the plasticity parameters via the development of a critical state model based on the results of triaxial tests. This was attained by considering loose sand specimens, at a predetermined TDA volumetric content, subject to three different confining pressures under a constant axial displacement rate. The calculated deviatoric stress versus axial strain curves, obtained via the modified Cam Clay model, captured the non-linear elastoplastic response obtained in the tests. Results indicated that the level of the shear strength is highly dependent on critical state friction angle which in turn depends on the TDA content. For the loose TDA-sand mixtures used in the present study, the effect of the TDA content demonstrates a reinforcement of the sand matrix. However this reinforcement diminishes as the TDA content increases.]]></description><pubDate>Wed, 23 Jun 2021 13:07:35 GMT</pubDate><guid>http://pubsindex.trb.org/view/1860414</guid></item></channel></rss>